During running cinder's CreateAndRestoreVolumeBackup scenario
we have race problem with backup deleting, because here [0] we
are waiting not for backup 'available' status, but for volume's
and at the deleting moment backup is still in 'restoring' status.
This patch fixes this problem.
[0] - 77cabd1769/rally/plugins/openstack/scenarios/cinder/utils.py (L372-L378)
Change-Id: I8ff9c349c5116211af7c47bb3fbeb7489144d26e
Closes-Bug: #1660965